This invention relates to torsion bars for independent suspensions, and more particularly, the invention relates to variable rate torsion bars.
Vehicle suspension assemblies may utilize torsion bars to increase the stiffness of the suspension and improve handling characteristics. For example, independent suspension that utilize coil springs frequently use torsion bars to provide supplemental stiffness to the coil spring at a different spring rate. Specifically, the torsion bar may be connected between a control arm and the frame. As the control arm moves vertically in response to inputs from the roadway, the torsion bar will rotationally deflect. Independent suspensions utilizing torsion bars can provide a significant packing advantage. However, a drawback of torsion bars is that they typically permit only a single spring rate. Multiple spring rates are desireable to provide refined handling characteristics. That is, it is desireable to provide different stiffness through the motion of the control arm. Therefore, what is needed is a multi-rate torsion bar that provides the packaging advantages of conventional single rate torsion bars while providing the suspension design with flexibility and optimization of handling characteristics.